Oil well pumping machinery



Jan. 16, 1945, "v s f AL 2.367.248

O IL WELL PUMPING MACHINERY Filed June 29; 1959 9 Sheets-Sheet 1 INVENTOR6 #frn 71 l mkers ATTORNEYS Jan. 16, 1945.

H. F; VICKERS ET AL OIL WELL PUMPING MAGHI NERY Filed June 29, 1959 9 Sheets-Sheet '2 INVE TORS #far/y f m'ers BY 60/76 a Ja .MM QMA ATTORNEYS Jan, 16, 1945 H. F. VICZKERS ET AL 2,367,248

1 01L WELL PUMPING MACHINERY Filed June 29, 1939 9 Sheets-Sheet 5 ATTORNEYS Jan. 16, 1945. H. F. VICKERS ET AL OIL WELL PUMPING MACHINERY 9 Sheets-Sheet 4 Filed June 29, 1939 w m m 5 a w W M 9 M m a m p 5- w a w w w I lflrllll #4,, 13 BY arm 0% 6W Jan. 16, 1945 H. F. VICKERS ETAL on; WELL PUMPING MACHINERY .Filed June 29, 1939 9 Sheets-Sheet 5 BY 7 epne Lerm ATTORMYS 1945- H. F. vlcKERs ETAL OIL WELL PUMPING MACHINERY 9 Sheets-Sheet 6 Filed June -29, 1939 ATTORNEYS 135 y F? Z 008% 'f/zrk Jan. 16,1945;

H. F. Vl3KER$ ETAL OIL WELL MACHINERY Filed June 29,1939 9 Sheets-Sheet 8 BY Hen/1:75;

A'ITO s Patented Jan. 16, 1945 UNITED STATES, PATENT OFFICE OIL PUMPING MACHINERY Harry F. Vickers and Kenneth R. Herman, Detroit, Mich asslgnors to Vickerl, Incorporated, Detroit, Mich.. a corporation ot Michigan Application June 29, 1939, Serial No. 281,926 1 22 Claims. ('01. 60'-52) The present invention relates to oil well pumping machinery.

It is common in the design of oil well machinery to provide a reciprocating member and cylinder therefor positioned directly over the well so that the sucker .rod of the well may be connected directly to the reciprocal member. Liquid under pressure is directed to a cylinder to raise the member and, in many cases, during the lowering stroke of the reciprocal member, the liquid is directed from the pumping cylinder to an accumulator cylinder in which a fluid is compressed or a weight lifted so that energy is stored as a result of the downstroke of the pumping element. Later on the upstroke of the pumping element this stored energy may be utilized to aid a pressure forming member in directing liquid under pressure to the reciprocal pumping element.

According to the present invention a pressure forming means is located between the pumping cylinder and the storage cylinder, which may be called an accumulator cylinder, and a means is provided to control the flow ofliquid from one of the cylinders to the other in either direction, the flow in each case being through the pressure forming means. In this way there is a substantially closed system between the two cylinders. However, due to inevitable leakage in the system, it is necessary to provide a means for replenishing the system at certain points in the reciprocal movement of the pumping element.

An object of the present invention is to provide a mechanism which is responsive to the movement of a reciprocal member either in the pumping cylinder or the accumulator cylinder or both which will permit the operating liquid to be taken by the pressure forming means from an independent supply and injected, into the closed system to replenish the supply of operating liquid. This replenishing apparatus is intended to operate automatically and is responsive to the quantity of liquid in the system.

Because of the extremelyheavy loads which are applied to the reciprocal pumping member and because-of the resulting high pressure which must be used to move the member, it is necessary that some means be provided to cause the proper acceleration and deceleration of move-. ment of the pumping member; Sudden movements of the reciprocal pumping member are to be avoided.

A further object of the invention is to provide a means for controlling this rate of acceleramal reversal of the system and to effect a delayed reversal during a replenishing cycle, this re.- versal being delayed automatically.

Another object of the invention has to do with the provision of a means for changing the operating speed of the reciprocal pumping element. A further object of the invention has to do with a pressure forming means formed of a plurality of pumps, one of which may be used for pilot pressure and others of which may be used singly or jointly to furnish pressure to the system whereby the speed of the system may be varied.

Means is also provided for cooling the operating liquid used in the system. Other objects of y the invention having to do with various embodiments and details of construction and operation thereof, will be further brought out in the following description. and claims.

In the drawings:

Fig. 1 is an illustration, partially diagrammatic and partiallyin section, of one oil well circuit embodying the present invention.

Fig. 2 is a view of a portion of Fig. 1 showing a valve in a shifted position.

Figs. 3, 4 and 5 are additional views of a portion of Fig. 1 showing the parts in difierent relative positions.

Fig. 6 is an illustration of a second oil well circuit in which a variable displacement pump is used.

Fig. 7 is a section taken on the lines 1-! of Fig. 6. v

Figs. 8, 9 and 10 are additional views of a portion of Fig. 6 showing the parts indifferent the circuit shown in Fig. 11.

Figs 17, 18, '19 and 20 illustrate portions of the circuit of Fig. 16 showing the relationship of jthe parts in different positions.

In Fig. 1 the simplest of the circuits embodying the invention is illustrated. The main elements of the circuit consist of a piston -cylinder motor 3fl3l, an accumulator tank 32, an air flash 3;, a pump 34 driven by a motor '35, a

through the lower part of the cylinder 3| to the piston 33 where it is fastened. The lower part of the cylinder 3| is provided with a main entrance port 43. A supplementary entrance port 44 leads from the port 43 to the bottom of the cylinder 3| and a checkvalve 45 permits passage to the cylinder only. A port 43, nor- -mally closed by a relief check valve 41, permits fluid to flow from the bottom of the cylinder 3| to the port 43. A tank 48 is provided to contain a supply of operating liquid and to facilitate the mounting of certain of the elements of the combination.

' ,The accumulator '32 consists of a vertical cylinder supported at the top by the tank 43. Within the accumulator 32 is a piston 53 which is connected to a vertical piston rod 5| passing through the top of the accumulator cylinder. A conduit 52 connects the lower part of the accumulator 32 with the lower end of the air flask 33 which consists of a vertically positioned cylinder. The

air flask is provided with a blow-off cock and anair flller valve 53.

The pump 34, which is a positive displacement vane type pump, is mounted on the inside of a wall of the tank 43 and the motor 35 is mounted to valve recess 15 by a conduit 83 which leads from the top of the accumulator cylinder 32. A tank conduit 34 is also connected to the valve recess 15 and the valve" is provided with an axial passageway which opens to the tank conduit 34. A conduit 31a connects'the conduit 31 with the lower end of the valve recess 13 in valve block 31. A spring 18a urges the valve 13 to an upward position, as shown in Fig. 1.

The valve 11 in the valve block 31 is to be actuated by a bell crank 83 which is pivoted at 31. The piston rod 5| is provided with cams 88 and 83 which are adapted to shift the valve 11 to reverse the system at each end of the stroke of-the pistons 33 and 53. An additional cam 93 is provided directly above the cam 89 to effect a delayed reversal after the operating liquid i the systemhas been replenished. Each of the valve recesses 15 and 13 is provided with spaced enlargeli ports and these'recesses are connected by passageways, the functions of which will appear as the operation of the circuit is described.

Referring now to the operation of the circuit just described, as the parts are shown in Fig. 1, the bell crank 33 has just been shifted so that piston 33 and piston rod 5| are each starting a downward stroke. When the system is first started, of course, the air flask 33 will be charged with a predetermined pressure of air and the operating lines must be filled with oil before operation will start. As shown by the arrows on the drawings, pressure is being furnished from V the top of the accumulator 32 through conduit 83 on the outside of the tank. Pump 34 has a main inlet-conduit 55 and an outlet conduit .53. A supplementary inlet conduit 51 is provided and a check valve 53 normally keeps this supplementary conduit closed.

. Also within the tank 43 is the directional control valve 33 which consists of a housing 59 provided with an axial recess 33, each end of which is closed by caps 0| and 62, respectively. Within the recess 33 is 'a slide'valve 33 which is adapted to be pilot operated within the recess and which is provided with narrowed portions 34 and 35. The recess of the directional control valve is provided with ports 33 and 33a which are connected respectively with conduits 55 and 53, leading to and from the pump 34. A conduit 31 connects the ports 43 and 44 in the cylinder 3| with a portg33 in the valve recess 33. A conduit 39 connects the top of the accumulator 32 with ports 13 and 1| formed in the recess 33.

Relief valves 12 and 13 are provided in conduits 31 and 39 to prevent excessive pressures from developing.

Referring now to the valve block 31, this block is provided with two parallel cylindrical recesses 15 and 13 in which is located, respectively, a cam actuated valve 11 and a pressure operated valve 18. The valve 33 is pilot operated and the pressure for operating this valve is controlled by the valves 11 and 13 in the valve block 31. A conduit 19 leads from the valve recess 15 to the end cap 3| on valve housing 59 and a conduit 83 leads from valve recess 13 to end cap 32. Each end cap 3| and 32 is provided with a check valve 3| and 31a so that pressure may flow freely into the axial recess 33. Each end housing is also provided with a needle valve 82 and 82a arranged so that liquid passing from the recess 33 to either conduit 19 or 33 will be restricted in its flow. Pilot pressure is furnished and past a restricted portion of the valve 11 to the conduit 19. This conduit 19 leads to the bottom of directional control valve housing 59 so that the directional valve 33 is shifted upwardly, as shown. With valve 33 in this position, continuously operating pump 33 receives liquid from cylinder 3| through port 43, conduit 31, ports 33 and 33 in valve housing 59, and inlet conduit 55. This liquid being received by the pump is under pressure because of the fact that the weight of the sucker rods on the polish rod 42 is being exerted on the operating liquid in the cylinder 3|. This liquid passes through pump 34 and to the accumulator cylinder 32 through outlet conduit,53, ports 33a and 1| in housing 59, and conduit 39. At this time, since there is pressure in conduit 31, there will be pressure in conduit 31a exerted against the lower portion of valve 18 and there is also pressure on the top of valve 18 from conduit 33 and cross passageway 92 in valve block 31.

During normal operation the valves will remain in the position shown in Fig. 1 until the piston 33 has reached a lower position shown by the dotted lines and until the piston rod 5| .has reached a position illustrated in Fig. 3. In

this position, it will be seen that the cam 89 has acted on the bell crank 33 to shift the valve 11 to a new position. In this new position the conduit 83 is blocked from the conduit 19 but is connected to the conduit 83 past restrictions in valves 11 and 18 and through a cross passageway 93 in valve block 31. Pressure through conduit 33 will be exerted on top of the valve 63 to shift it downwardly. Liquid from the lower portion of the recess 33 will flow past the restriction'needle-valve 82 into the conduit 19, this conduit being connected to the tank at ths time through the axial passageway 35 in valve 11 and the conduit 84.

The pressure on the top of valve 33 exerted.

' reversed in tion shown in Fig.2. As the valve 63 is shifted, the tapered portion above the restricted portion 64 on the valve, graduallycuts oil the outlet conduit 56' from conduit 68 leading to the accumulator. At the same time the tapered portion below the restriction 64 gradually opens the conduit 56 to conduit 61. Meanwhile, the shifting of the valve has cut off the conduit 61 from the conduit 55 and opened the conduit 69 to the conduit 55. The rate of movement of this change can be positively controlled by regulation of needle valve 02. With the valve 63 in the position shown in Fig. 2, the outlet of the pump will be connected to the cylinder 3| and the ac-- cumulator cylinder 32 will be connected to the inlet of the pump so that the flow of liquid is the system and the pressure from the 'otulet of the pump is exerted on the piston 30 to raise the same.

' In any hydraulic system there is inevitable leakage especially when the system is operating under the high pressures which are necessary when pumping oil from deep wells. The present circuit provides a means for replenishing the operating liquid which normally circulates back and forth between the cylinder 3I and the cylinder 32 in a closed system. In the present circuit the leakage in the system would be direct v ly evidenced by the lowermost position of piston.

30 since any decrease in the quantity of operating liquid-in the system 30 to reacha lower position than that .shown by the dotted lines before the cam 89 could operate to reverse the system. The port 43 in the lower part of cylinder 3| is positioned in the side wall of the cylinder so that when'piston 30 reaches the port it will close it off. When this happens a replenishing is necessary.

Normally, of course, on the downstroke of piston 30, the pump 34 is receiving liquid under pressure from cylinder 3| through conduit .61.

If the port 43 is closed, the condu t 61 will soon be drained of liquid and there will be a definite lowering of pressure in conduit 61 and in connecting .conduit 61a..: ;In view of the fact that the top of valve 10 is always subject to pressure from conduit 83 through cross passageway 92, the valve 18 will be shifted to the position shown in Fig. 4 when pressure in conduit 61a is lowered. With. the valve 13 in this position, it will be seen that the cross'passageway 03 is blocked y from the conduit 60. Consequently, when the bell crank 86 and the valve 11 is shifted by cam 89 to the positions shown in Figs. 3 and 4, the pilot pressure from conduit 83 will not reach the valve 63 to shift the same. I Instead, both conduits 19 and 80 are connected to the tank. Valve 11 connects conduit 19 to the tank through axial passage 65. Conduit 80 connects to the tank past valve 18, through a cross passage 05 in valve block 31, and through axial passage 85 in valve 11. The pump 34, therefore, will continue to direct liquid under pressure to the accumulator 32, but this liquid will be coming from the supplementary inlet 51 which is open to the independent supply of operating liquid in the tank 43. Because of this action, the piston rod 5| will continue in its downward movement until the cam 90 actuates the bell crank 86 and the valve 11*. to the position shown in' Fig. 5. With the valve 11 in this position, pressure may pa'ss from conduit 83 past various restricted portions in valve 11 to a cross passageway 94 which leads to the conduit 00. There will thus be a belated shifting of valve 63 after the liquid in the system has been replenished.- As soon as the valve 63 is shifted, pressure will again, be exerted in conduit 61 and conduit 61a so that the valve 18 will be again shifted upwardly to the position shown in Fig. 5. During the reversal stroke, after replenishment,'valves 11 and 10 will maintain the position shown in Fig. 5 until the cam 88 again contacts the lower arm of the bell crank 86 to shift it to the position shown in Fig. 1. At this time pressure will be again directed from pilot conduit 83 through conduit 19 to the lower part of valve 63. The valve 63' will be shifted upwardly,-the rate of shifting in this case being controlled by the setting of restriction needle valve 82a. i

The relief valve 41 in the lower part of cylinder 3| is provided in the event of live failure to release liquid trapped in the bottom of the cylinder after the piston 30 passes the port 43, in

wouldpermit the piston,

' cylinders I06 and I01.

other words, to provide relief for the dashpot action of the base of the cylinder. Similarly,

.at the beginning of the reversal, after replenishing, liquid will be first furnished to the lower part of piston 30 past the check valve 45.

In the circuit shown in Fig. 6 many of the elements are the same as illustrated in, and described. in connection with, Fig. 1. In this circuit, however, a variable displacement .pump I00 is substituted for the vane type pump in Fig, 1

[and there is no necessity for a directional control valve. The pump I00 may be any well known type of variable displacement pump having a movable head IOI for varying the displacement of the pump and also the direction of the flow of liquid through the pump. A pressure dome I02 surrounds the pump and this dome is adapted to receive and deliver liquid to an opening I02a in the pump which serves alternately as an inlet and an outlet. This pressure dome I02 is connected to the top of the accumulator 32 by a conduit 69a. The other opening of the pump which is adapted to serve alternately as an inlet and an outlet is connected to the conduit '61 and a supplementary inlet conduit 51 is provided as before.

Referring to the sectional view of the pump shown in Fig. '1, it will be seen that the movable head IOI is adapted to be shifted by a pilot operated rod I03. Pistons I04 and I05 at the respective ends of the rod are located respectively in Adjustable stops I08 are provided at each end of the cylinders to limit the movement of the rod I03. When the movable head IOI isshifted to the right to its extreme position, the pump I00 will be delivering liquid from the cylinder 3I to the accumulator 32 as will be described later. When the movable head is shifted to the left to itsuextreme position, the

pump will be delivering liquid under pressure from the accumulator I be seen that the control rod I03 is shifted by pilot pressure in the same manner as the directional control valve was shifted in Fig. 1. A spring 2 is placed in the pressure dome I02 to tend to shift the movable head to the right, as viewed in Fig. '1, so that, in starting, liquid will be directed to the accumulator cylinder 32.

In the operation of the circuit shown inFig. 6,

assuming that the air flask a is-charged and the system is normally operating with a specified amount of operating liquid, when the parts are in the positionshown in Fig. 6, the piston 30 is ready to start a downward stroke. Th bell crank 86 and the valve 11 have been moved, to the position shown, by the cam 88 thereby connecting pilot pressure conduit 83 with control conduit 18a.

Pressure is thus directed to cylinder I01, to shift the movable head IM to the right and the rate of this movement is controlled by the needle valve IIO. Liquid passes from the cylinder I08 to the tank through the conduit 80a past valve 18,

position shown in Fig. 8. If no replenishment is necessary there will be a normal reversal, pilot pressure passing from lin 83 past valve 11,

.through cross passageway 93 and past valve 18 to conduit 80a. This will shift the control rod I03 to the left and liquid will pass out of cylinder I01 through the needle valve I I I to the tank through conduit 19a and the axial passageway 85 in valve 11. The direction of flow of operating liquid will thus be reversed.

In case the system is in need of replenishment of operating liquid, as described in connection with Fig. 1, the port 43 will be cut oil from the cylinder 3| by the piston 30. This will cause a' reduction of pressure in conduit 81a and the result will be that valve 18 is shifted downwardly by pressureon its top surface and the pump will start to draw liquid from the supplementary inlet 51. The shifting of the valve 18 to the position shown in Fig. 9 will block the above described normal reversal due to valve 18 cutting ofi conduit 93 from conduit 80a. Reversal will be delayed until the accumulator is filled with enough liquid to cause the cam 90 to contact the top arm of bell crank 86, as shown in Fig. 10. At this time the shifting of valve 11 to the position shown in Fig. 10 will permit pilot pressure to pass from conduit 83 past various restricted portions of valve 11 to cross passageway 94 where it is connected tothe control conduit 80a; As soon as reversal is affected, pressure will rise in conduit 61 so that the valve 18' will again be shifted to its uppermost position and the upward stroke of piston 30 after the replenishment. will take place with valves 11 and 18 in the positions shown in Fig. 10.

After either a normal reversal by cam 89 or a delayed reversal by cam 80, the piston 30 and the piston rod 5| will rise until the cam 88 contacts the lower arm of the bell crank 88. At this time the valve 11 will again be shifted to the-position shown in Fig. 6 and the operation will continue as described.

In Fig. 11 is shown a third oil well circuit embodying the invention. The main difference between the circuit of Fig. 11 and the circuits shown in Figs. 1 and 6 lies in the pressure forming means, though there are other diflerences in detail which will be. brought out. The pressure forming means includes a plurality of pumps, three in number, one of which is to be'used as a pilot pump and the remaining two to be used as power pumps for the system. The two main pumps are designed so that they will have different volume ranges so that two speeds can be achieved by using one or both of them. Two speeds are desirable since the operator may desire to determine, at various times, ifthe well can supply more 011 than is being delivered by one pumping unit.

Referring to Fig. 11, the piston-cylinder motor 30-3I is the same as previously described. An accumulator I20, in Fig. 11, is formed as one cylinder, a piston I2| being located therein to separate compressed air in the top of the cylinder and operating liquid in the lower portion. A relief and charging valve I22 is provided at the top of the accumulator to control the air charge. A piston rod I23 extends downwardly from the piston |2I and on the end of the rod is formed a cam member which has three cam surfaces 88a, 89a and 80a.

Theaccumulator I20 is mounted on a tank I24 in which is mounted a valve block I25. This valve block is provided with two parallel valve recesses'15a and 16a in which are mounted, respectively, a cam actuated valve 11a and a pilot operated valve 18b. -A bell crank 88a is operably connected to the valve 11a.

Mounted on the top of the tank I24 is amotor I28 provided with a drive shaft I21 whichextends downwardly into the tank. A pump housing I28 surrounds the drive shaft I21 and in the housing are pumps I28, I30 and I3I. Directly adjacent the pump housing I28 is a valve housing I32 in which are housed a pump conilzrol valve I33 and a. directional control valve The pump control valve I33 is adapted to be operated by pressure acting on one or both ends and the valve is arranged to have two lowermost positions depending on th position of a cam member I35 positioned directly beneath the valve. The directional control valve I34 is similar to the directional control valve described in connection with Fig. 1. This valve is pilot operated and-is arranged to control the direction of flow of operating liquid between the cylinder 3| and the accumulator I20. The operation of valve I34 is to be'controlled by valves 11a and 18b. The

rate 01' movement of the directional controlvalve I34 is controlled by needle valves 82 and 82a, check valves 8| and 8Ia being provided to admit pressure to the valve recess at each end, as in Fig. 1. v

The cylinder 3| is connected to the recess of 'valve I34 by a conduit I36. The lower end of the valve 182: is connected to conduit I38 by a conduit I31. The lower part of the accumulator I20 is connected to the recess of valve I34 by a conduit I38. Various interconnecting passageways are provided in housings I28 and I 32 and these passageways will be described in connection with the operation of the system. The pilot pump I3| delivers pilot pressure to valve recess 15a in valve block I25 through a conduit I40. Valve recess 15a is connected to the top of valve I 34 by a conduit MI and is connected to the lower end of valve I34 past valve 18b through a conduit I42. tank recess a and the upper end of recess 15a is connected to the tank by a port opening I43. A spring I44 urges the valve 18b to its downward position.

As the parts stand in Fig. 11, the operating liquid in the system is being replenished. Just prior to this point in the operation, the valves Valve 11a is provided with an axial,

- respective outlets I48 and I49.

' end of valve I33 through a conduit I54.

were in the positions shown in Fig.13, and the piston 30 was descending. Referring'to Fig. 13 it will be seen that liquid under pressure is passing from conduit I36 and the cylinder 3I to the directional control valve I34 where a restriction in the valve permits the liquid to enter passageway I45 leading to pump control valve I33. A

restriction in valve I33 permits the liquid from cylinder 3| to pass to inlet conduits I46 and I41 of power pumps I29 and I30, respectively. This liquid will pass through the pumps and enter the These' outlets lead around the valve I33 past check valves I50 and I5I to a common conduit I52. This conduit I52 leads to the valve I34 and with, the valve in the position shown in Fig. 13, liquid from the pumps may pass a restriction in the valve to the accumulator conduit I38. At this time it will be seen that pressure from conduit I36 is exerted on the top of valve I33 through a conduit I53. The pressure passing from conduit I52 to the accumulator conduit I38 is exerted on the lower The pressure in conduit I36 coming from the cylinder 3I is also exerted on the lower end of valve 18b so that the valve is held in itsuppermost position against the action of spring I44. Bell crank 86a and the valve 'I'la had been shifted to the position shown in Fig. 13 by cam 88a as the piston 30 reached the top of its stroke and the piston I2I reached the bottom of its stroke. With valve 11a in this position, pilot pressure from conduit I40 passes a restriction in valve 11a to conduit I where it is. exerted against the top of valve I34 to maintain the same in the position shown in Fig. 13. Conduit I42, leading from the lower end of the recess of valve I34, is connected to the tank past valve 18b througha cross passageway I55 in valve block I25. This passageway connects to the axial passageway 85a in valve 'I'la, this passageway leading to the tank through port I43 in the top of the valve recess.

With valve I33 in the position shown in Fig. 13, it will be seen that both pumps I29 and I30 are functioning to pass liquid through the system. If

. outlet I48 of pump I29 is, however, still connected to the common outlet conduit I 52.

If there were to be a normal reversal of the system, as 'piston 30 approached a lowermost position, just above port 43, the cam 89a would, contact the upper arm of bell crank 86a to shift the valve 11a to the position shown in Fig. 12. With the valve in this position, pilot pressurepasses from conduit I40 past a restriction in valve 11a to a passageway I56 leading to valve recess 16a. Since valve 18b is in its uppermost position, the pilot pressure may pass around a restriction in the valve to conduit I42 from which it will be directed to the lower end of directional control valve I34. The directional control valve will thus be shifted to its uppermost position, as shown in Fig. 12, the liquid from the top of the valve passing through conduit I4I' to the tank via the tank passage'85a and port I43. With-reference to Fig. 12, it will be seen that the accumulator conduit I38 is now connected past valve I34 to passageway I45. Due to the position of valve I33, liquid will passfrom the passage I45 to the inlets'of pumps pumping piston 30 will rise.

If the quantity of operating liquid in the closed system becomes decreased due to leakage, when I the piston 30 descends in its lowering stroke, it will pass the port 43 and block'the same. This will happen-when the valves are in the position shown in Fig. 13 and since the pumps can no longer draw liquid from conduit I36, there will be a decrease in pressure in this conduit and in conduit I53, and, consequently, a decrease in pressure on the top of valve I33. The pressure on the bottom of valve I33 is still exerted from the accumulator through conduit I54. The result would be a shifting upward of the valve I33 to the position shown in Fig. 11. The decreasein the pressure in conduit I36 will also have its effect on the pressure in conduit I31 so that the valve 18b will be urged to its lowermost position by-spring I44, as

. shown in Fig. 11.

these positions, when the cam 89a contacts the upper arm of hell crank 86a and shifts the valve Ila to the position shown in Fig. 11, there will be .no reversal as would occur normally due to the fact that pilot pressure from conduit I40 will be blocked from conduit I42 by valve 18b which the accumulator I38. The operating liquid in the p system will consequently be increased in quantity and the piston I2I will continue to rise until the cam 90a moves the bell crank 86a to the position shown in Fig. 14. This shifts the valve 11a to its lowermost position and in spite of the fact that valve 181) is still blocking passage I56, pilot pressure may pass from conduit I40 past various restrictions in valve Ila to the cross passage I55 and around valve 18b to control conduit I42. Valve I34 will again be shifted upward and the system will be reversed with liquid passing from the accumulator to the cylinder 3|.

A relief valve I60 is connected to conduit I38 .Here the oil may be cooled and will pass again to the tank through a conduit I66. A baflle plate I61 prevents the oil being cooled from coming into contact with the coupling between the motor and the shaft I21.

Deceleration safety valves I68 and I69 are provided at the cylinder ends of conduits I36 and I38 respectively. These safety valves are so arranged that if flow from the cylinders exceeds a certain quantity, the valves will be shifted against biasing springs to restrict the flow. In case of power failure, for example, the system will 'not get out of control to cause breakage or damage.

In Fig. 16 is illustrated an' oil well circuit which is a modification of the oil well circuit shown in With valves I33 and 18b in degrees.

Fig. 11. This circuit differs from that illustrated inFig. 11 in that a-valve I10 in a block I" is provided to control the pilot pressureto and from valve I34 and a valve "3a is substituted for valve I33 of Fig. 11, to perform the functions of valve I33 and also to serve as an interrupter valve in the place of valve 18b found in Fig. 11. Pilot pressure is furnished to the valve block IlI through conduit I40 from pilot pump ISI. This pilot pressure will be directed to the top oi valve I04 through a conduit I when valve I10 has been moved by cam 80a and bell crank 86a to the position shown in Fig. 1'7. A tank passage IIa is located in valve "0. a

When the valve I is shifted by the cam 89a to the position shown in Fig. 16, reversal of the system will normally take place with pressure being directed from pilot conduit I40 to conduit I42a which leads past valve 133:; in the position shown in eitherFig. 17 or Fig. 19 to conduit I42 which leads to the bottom of valve I34. Delayed reversal is caused by valve I33a being shifted, to the position shown in Fig. 16. As described in connection with Fig. 11, this shifting will occur when the conduit I36 is blocked by the piston 30 and the pressure beneath the valve I330 will urge the valve upwardly. Conduit I42a will then be complished during this interrupted or delayed reversal. The path of pilot liquid to effect delayed reversal is shown by the dotted arrows in Fig. 16. In Fig. 19 the valve I33a is illustrated in its lowermost position when the cam I350 is rotated 180 In this position, pump I30 will be bypassed and pump I29 will be operating. In Fig. 20 the valve I34 is shown in its shifted position to cause a lowering of piston I20 and a raising of piston 30.

Since the operation of the circuit shown in Fig. 16 is very similar to that of Fig. 11, except for the differences above noted, the details of the flow of operating liquid and the shifting of the valves will not be repeated.

We claim:

1. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for resisting the entrance of liquid to said cylinder, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means, a pilot operated shiftable means adapted to control the direction of liquid under pressure through said pressure forming means and to and from said cylinders, a supply of operating liquid, unidirectional valve means connecting said supply with the inlet of said pressure forming means, valve means responsive to movement of one of said reciprocal members for directing pressure to saidpilot operated means to shift the same, and

. additional valve means responsive to abnormal movement of one of said reciprocal members re- Tsllltlllglll closure of the outletpo'rt of one or said 'scylindersadapted' to "delay the shifting of said pilot-operated means, and thereby cause a replenishing of liquid from said supply to said system "during said delay.-

2. In combination, an auxiliary cylinder for containing an operating liquid, means for resisting the entrance oIliquid thereto, a motor cylinder, a reciprocal member in. said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means, conduits connecting said cylinders with said pressure forming means, means shiitable to direct operating liquid from one of said cylinders to said pressure forming means and from said pressure forming means to the other of said cylinders alternately in a closed system, a supply of operating liquid, a source of pilot pressure, valve means responsive to the quantity of operating liquid in said auxiliary cylinder adapted to direct pilot pressure to said shiftable means to control the position thereof, and an auxiliary valve normally biased to one position, and adapted to be shifted to a second'position to block pilot pressure from said shiftable means when said reciprocal member has moved through a given distance whereby reversal of movement of said reciprocal member is delayed, and means responsive to the movement of said reciprocal member arranged to cut-oil the inlet of said pressure forming means from said motor cylinder and to open it to said supply of operating liquid to permit a replenishment of liquid in said closed system, and a passageway permitting flow to the operating side of said reciprocal member when said inlet is cut mi.

3. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for resisting the entrance of liquid to said cylinder, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means, conduits connecting said cylinders with said pressure forming means, means shiftable to direct operating liquid from one of said cylinders to said pressure forming means and from said pressure forming means to the other of said cylinders alternately in a closed system, a

supply at operating liquid, a source of pilot Dressure, valve means responsive to movement of one of said reciprocal members adapted to direct pilot pressure to said shiftable means to control the position thereof, and an auxiliary valve normally biased to one position, and adapted to be shifted to a second position to block pilot pressure from said shiftable means when the other of said reciprocal members has moved through a given distance whereby reversal of movement of said reciprocal members is delayed, and means responsive to the movement of one of said reciprocal members arranged to cut-oil the inlet of said pressure iorming means from said motor cylinder and to open it to said supply of operating liquid to permit a replenishment of liquid in said closed system, and a passageway permitting flow to the operating side of said reciprocal member when said inlet is cut oil.

4. In combination, an, accumulator cylinder for containing an operating liquid, an accumulator reciprocal member in said cylinder, means acting on said member for resisting the entrance of liquid to said cylinder, 9. motor cylinder, a reciprocal member in said motor cylinder adapted to be opclosed system, a supply of operating liquid, a source of pilot pressure, valve means responsive to movement of one of said reciprocal members adapted to direct pilot pressure to said shiftable means to control the position ther'eof, and an auxiliary valve normally biased to one position, and adapted to be shifted to a second position to block pilot pressure from said shiftable means when the other of said reciprocal members has moved through a given distance, whereby r versal of said reciprocal members is delayed, and means responsive to the movement of one of said reciprocal members arranged to cut-ofl the inlet of said pressure formin means from said motor cylinder and to open it to said supply of operating liquid to permit a replenishment of liquid in said closed system, said valve means being responsive to additional movement of said accumulator reciprocal member to connect said shiftable means to said pilot pressure to reverse the system after a predetermined replenishment of the closed system, and a passageway permitting flow to the operating side of said motor member when said inlet is cut off.

' 5. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for resisting the entrance of liquid to said cylinder, a motor comprising a cylinder having an inlet, and a reciprocal member in said motor cylinder adapted to be operably connected to the sucker. rod of a pump in a well, and a passage in said motor to permit flow thereto when the inlet is closed, a pressure forming means having inlet and outlet ports, a pilot operated directional valve adapted to direct liquid under pressure to and from said cylinders through said pressure forming means in a closed system, a supply of operating liquid, a unidirectional valve means connecting the inlet of said pressure forming means with said supply, valve means responsive to movement of one of said reciprocal members for directing pressure to said pilot operated valve to shift the same, means to control the rate of movement of saidpil'ot operated valve to control the acceleration and deceleration of said reciprocal members, closing means for said motor inlet operable as a consequence of a reduced quantity of liquid in said closed system, and additional valve means responsive to the closing of said closing mean to delay the shifting of said pilot operated valve, and

thereby cause a replenishing of liquid to said closed system by reason of said pressure forming mean drawing liquid from said supply through the unidirectional valve means during said delay.

6. In combination, a cylinder for containing an operating liquid and means including a reciprocal member for resisting the entrance of liquid thereto, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means comprising a variable displacement pump, a movable member on said pump arranged by its movement to control the direction and volume of output of said pump, conduit means connecting said pump with said cylinders, means including a unidirectional valve connecting said pump to a supply of replenishing fluid, pilot operated shiftable means operably connected to said movable member to shift the same, a source of pilot pressure, valve means responsive to movement of one of said reciprocal members for directing pilot pressure to said pilot operated means to shift the same, valve means responsive to movement of one of said reciprocal members adapted to close the inlet to said one reciprocal member, and additional valve means similarly responsive to delay the shifting of said pilot operated means and thereby cause additional operating fluid to be supplied to one of said cylinders to replenish the system.

7. In combination, an accumulator cylinder for containing an operating liquid, a reciprocal member adapted to be shifted by changes in quantity of operating liquid in said cylinder, means resisting the entrance 0! liquid into said cylinder whereby liquid therein will be under pressure, a motor cylinder, a motor member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a conduit leading to an entrance port at one end of said accumulator cylinder, a conduit leading to an entrance port at one end of said motor cylinder, a pressure forming means having inlet and outlet ports, means disposed in said conduits and arranged to direct operating liquid from one of said cylinders to the other through'said pressure forming means, and means for causing the replenishing of the supply of operating liquid normally passing between said cylinders comprising a unidirectional valve means connecting the inlet or said pressure forming means with a supply of liquid, and a shiftable valve 'means exposed at one end to pressure'in the conduit leading to the motor cylinder, said last named valve means normally permitting reversal ofthe system but arranged to shift to delay reversal when the supply of operating liquid in the system is diminished to the extent that said motor member may pass and close said unidirectional valve from said supply, and a passageway permitting flow to the operating side of said motor member when said conduit port is closed by said motor member.

8. In combination, an accumulator cylinder for containing an operating liquid, a reciprocalmember adapted to be shifted by changes in quantity of operating liquid in said cylinder, means resisting the entrance of liquid into said cylinder whereby liquid therein. will be under pressure, a motor cylinder, a motor member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a conduit leading to an entrance port at one end of said accumulator cylinder, a conduit leading to an entrance port at one end of said motor cylinder, a pressure forming means having inlet and outlet ports, valve means disposed in said conduits and arranged to direct operating liquid from one of said cylinders to the other through said pressure forming means, means for replenishing the supply of operating liquid normally passing between said cylinders comprising a unidirectional valve mean connecting the inlet of saidpressure forming 'means with a supply of liquid, and a shiftable valve means exposed at one end to pressure in the conduit leading to the motor cylinder, said last named valve means normally permitting reversal of the system but arranged to shift todelay reversal when the supply of operating liquid in the systemis diminished to the extent that said motor member may pass and close the conduit port leading to the motor cylinder, said replenishment taking place automatically during said delayed reversal by reason of said pressure forming means drawing liquid from said supply through said unidirectional valve and passing it to said accumulator cylinder, and means responsive to the movement of said reciprocal member by reason of the flow of replenishment liquid to said accumulator cylinder to eflect a delayed reversal upon the. operation of said replenishing means, including a passage permitting flow to said motor when its inlet is closed by the motor member.

9. In combination, an accumulator cylinder for containing an operating liquid, a reciprocal member adapted to be shifted by changes in quantity of operating liquid in said cylinder, means resisting the entrance of liquid into said cylinder whereby liquid therein will be under pressure, a motor cylinder, 'a motor member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a conduit leading to an entrance port at one end of said accumulator cylinder, a conduit leading to an entrance port at one end of said motor cylinder, a passageway permitting flow from said motor cylinder conduit to said motor cylinder when said entrance port is closed, a pump having inlet and outlet ports adapted to be connected alternately to said conduits and having an inlet ort connected to an independent supply of operating liquid, connecting, means operative to connect said closed system with said supply, a first means to effect normal reversal of flow between said tank and cylinder when the quantity of operating liquid is above a predetermined volume, a second means operative to delay the eiIect of said last named means, said second means and said connecting means being pressure responsive members subject to pressure at the pump inlet .during one stroke of said motormember and being rendered operative by reduction in such pressure, and means to close said pump inlet from the motor cylinder upon predetermined reduction in the quantity of said body of liquid thereby causing said reduced pressure..

10. In combination, an accumulator cylinder for containing an operating liquid, a reciprocal member adapted to be shifted by changes in quantity of operating liquid in said cylinder, means resisting the entrance of liquid into said cylinder whereby liquid therein 'will be under pressure, a motor cylinder, 9. motor member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a conduit leading to an entrance port at one'end of said accumulator cylinder, a conduit leading to an entrance port at one end of said motor cylinder, a pressure forming means having inlet and outlet ports adapted to be connected alternately to said conduits and having an inlet port connected through an unidirectional valve to an independent supply of operating liquid, valve means for directing liquid toand from said conduits through said pressureforming means, cam means on said reciprocal member for shifting said valve means at the end of a normal stroke to cause reversal of the flow through said conduits, a valve responsive to movement of said motor member for blocking the reversal effect of said valve means and thereby causing tin-amplified stroke of the reciprocal member by reason of liquid being drawn from said supply and passed to said accumulator cylinder, said cam means being formed to impart an additional movement to said valve means when the stroke of said reciprocal member is amplified by reason of the delayed reversal whereby reversal of the system may be effected.

ll. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for re slsting the entrance of liquid to said cylinder, a motor cylinder, a reciprocal member in said motor cylinder'adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means comprising a plurality of pumps. a pilot operated directional control valve, a selector valve for directing the delivery of one or more of said pumps to said control valve whereby it may be further directed to one of said cylinders, a supply of operating liquid, means connecting the inlet of one of said pumps to said supply, valve means responsive to movement of one of said reciprocal members for directing pressure to said pilot operated valve to shift the same, and additional valve means responsive to prolonged movement, of one of said reciprocal members re- "sulting in the closure or the outlet port of one of said cylinders adapted to delay the shifting of replenishing of operating liquid from said supply to said system during said delay.

12. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for resisting the, entrance of liquid to said cylinder, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means comprising a, plurality of pumps, a pilot operated directional control valve, a selector Valve fordirecting the delivery of one or more of said pumps to said control valve whereby it may be further directed to one of said cylinders, a supply of operating liquid, means connecting the inlet of one of said pumps to said supply, valve means responsive to movement of one of said reciprocal members for directing pressure to said pilot operated valve to shift the same, and additional valve means adapted to deadditional valve means and said selector valve being responsive to prolonged movement of one of said reciprocal members resulting in the closure of the outlet port of the respective cylinder whereby operating liquid in said system will be replenished by one of said pumps from said supply during said delay.

13. A pumping system combining a motor member and a balancing member each to be shifted, a relatively high volume pumping mechanism for impartingmovement to said members, a second pumping mechanism for imparting a difierent rate of movement to said members, a shiftable control mechanism for said pumping mechanisms comprising an element shiftable within a casing adapted in one shifted position to direct fluid from said first mentioned pump to impart movement to one of said member and to bypass the other of said pumps, adapted in a second position to direct fluid from both of said pumps to one of said members, and adapted in a third position to bypass said first mentioned pump and direct pressure from said second pump to one of said members, a main valve for determining the action of said pumping mechanisms, conduits connecting said balancing member and motor member through said main valve to inlets and outlets of said pumping'mechanisms so as to permit reversible flow between said members, a control valve for determining the action of said main valve, means actuated by the movement of one of said members for mechanically shifting the controlyalve, means hydraulically actuable by fluid passed by the control valve for operating the main valve, and means responsive to reducto the sucker rod of operating circuit including apressure forming tion fn'pressure in the motor supp y conduit for delaying the movement of the main valve, said shlftable control mechanism being also responsive to reduction in pressure in the motor supply conduit whereby it will be shifted to its third position to eflect replenishing of operating fluid in the system;

l4. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for resisting the entrance of liquid to said cylinder, a motor cylinder, a reciprocal member in said motor cylinder'adapted to be operably connected a pump ina well, a closed means comprising a'plurality of pumps, a pilot operated directional control valve, a selector valve for directing the delivery of one or more-of saidpumps to said control valve whereby it-,may be further directed to one of said cylinders, a supply of operating liquid, means connecting one of said pump to said supply, and valve means respon sive to movement of one of said reciprocal,members for directing pressure to said pilot operated valve to shift the same, said selector valve being normally biased to one position, and adapted to. second position to block pilot be shifted to a pressure from said shiftable means, means to cut oil the motor inlet from the inlet of said pressure forming means when said motor reciprocal member has moved through a given distance, and means responsive to consequent reduced pressure at said pressure forming means inlet to open said inlet to said supplyof operating liquid to permit a replenishment of liquid in said closed system.

15. In combination, a cylinder for containing an operating liquid, a reciprocal member in said cylinder, means acting on said member for resisting the entrance of liquid to said cylinder, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a closed operating circuit including a pressure forming means comprising a plurality of pumps, a pilot operated directional control valve, a selector valve for directing the delivery of one or more of said pumps to said control valve whereby it may be further directed to one of said cylinders, a supply of operating liquid, valve means responsive to movement of one of said reciprocal members for directing pressure to said pilot operated'valve to shift the same, said selector valve being normally biased to one control position but arranged in said closed circuit to be shifted in response to excessive movement of one of said reciprocal members to a second position to by-pass one of said pumps and block pilot pressure from said control valve thereby delaying reversal, means to cut oil the motor inlet from the inlet of said pumps also responsive to the excessive movement of said "one reciprocal'member, and means responsive to consequent reduced pressure at said pump inlet to open said inlet to said supply of operating liquid to liquid in said closed system.

'16. In combination, an auxiliary cylinder for containing an operating liquid, means for resisting the entrance of liquid thereto, a motor cylinder, a reciprocal member insaid motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means comprising a continuously operated motor and a plurality of pumps driven thereby, one of said pumps being adapted to serve as a pilot pump, a selector valve for directing the output of the permit a replenishment of other of said pumps, conduits connecting said cylinders with said selector valve, means shiftable to direct operating liquid from one of said cylinders to said pressure forming means and from said pressure forming means to the other of said cylinders in a closed system, a supply of operating liquid, means connecting one of said pumps to said supply, valve means responsive to flow of .operatingliquid to and from said auxiliary cyl- 10 inder adapted todirect pilot pressure from said pilot pump to said shiftable means to control the position thereof, an auxiliary valve normally biased to one position, and adapted to be shifted to a second position to block pilot pressure from [5 said shiftable means, mean to cut on the motor inlet'from the inlet of said pressure formin means when said reciprocal member has moved through a given distance, means responsive to consequent reduced pressure at said pressure forming means inlet auxiliary valve to its second position, and means responsive to consequent reduced pressure at said pressure forming means inlet to open said inlet to said supply ofoperating liquid to permit a replenishment of liquid in said, closed system.

17. In combination, an auxiliary cylinder for containing an operating liquid, means for resisting the entrance of liquid thereto, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means comprising a continuously operated motor and a plurality of pumps driven thereby, one \of said pumps being adapted to serve as a pilot pump, a selector valve for directing the output of the other of said pumps, conduits connecting said cylinders with said selector valve, means shiftable to direct operating liquid from one of said cylinders to said pressure forming means and from said pressure forming means to the other of said cylinders in a ply of operating liquid connected to but normally closed from the inlet of one of said pumps, valve means responsive to flow of operating liquid to rect pilot pressure from said pilot pump to said shiftable means to control the position thereof, said selector valve being normally biased to one position, and adapted to be shifted to a second position to block pilot pressure-from said shift able means when said reciprocal member has moved through a given distance to close an inlet of said motor cylinder and thereby reduce the pressure in the inlet of one of said pumps by cutting off supply of liquid from said motor cylinder, and means responsive to said reduction in pressure to open said supply of operating liquid to said pump to permit replenishment of liquid in said closed system.

18. In combination, an auxiliary cylinder for containing an operating liquid, means for resisting the entrance of liquid thereto, a motor cylinder, a reciprocal member in said motor cylinder adapted to be operably connected to the sucker rod of a pump in a well, a pressure forming means comprising a continuously operated motor and a plurality of pumps driven thereby, one of said pumps being adapted to serve as a pilot pump. a selector valve for directing the output of the other of said pumps, conduits connecting said cylinders with said selector valve, means shiftable to direct operatingliquid fromone of said cylinders to said pressure forming means and from said pressure forming means to the other oi. said cylindersina closed system, a supply of to cause shifting of said closed system, a supand from said auxiliary cylinder adapted to dioperating liquid connected to but normally closed from the inlet of one of said pumps, responsive to flow 0! operating l quid to and from said auxiliary cylinder adapted to direct pilot pressure from said pilot pump to said shiftable means to control the position thereof, said selector valve being normally biased to one position, and adapted to be shifted to a second position to bypass one of said pumps and block pilot pressure from said shiitable means when said reciprocal member has moved through a given distance to close an inlet 0 said motor cylinder and thereby reduce the pressure in the inlet of another oi said pumps by cutting or! supply of system.

19. In a well pumping system, a motor cylinarranged between said der, an inlet thereto, a reciprocal motor member in said cylinder arranged to close said inlet when positioned adjacent thereto, a passageway permitting flow to the operating side or said motor member when said inlet is closed, a balancing tank to be connected to said cylinder, a pump tank and cylinder for directing operating liquid from one to the other alternately in a closed system, an independent supply of liquid, and pressure responsive connecting means operable by reduced pressure caused by a closing of said cylinder inlet by said motor member to open said supply to said closed system to eilect replenishing.

20. In awell pumping system, a motor cylinder, an inlet thereto, a reciprocal motor member in said cylinder arranged to close said inlet when positionedv adjacent thereto, a passageway permitting flow to the operating side of said motor member when said inlet is closed, a balancing tank to be connec to said cylinder, a pump arranged between said tank and cylinder for directing operating liquid from one to the other in a closed system, a first means to effect normal reversal oi flow between said tank and cylinder when the quantity of operating liquid in the closed system is above a predetermined amount, to delay the eflect, of said last inlet is closed by said motor member by reason of a reduced quantity of operating liquid, an independent supvalve means connecting means pendent supply of the closing of said cylinder inlet to open said supply tosaid closed system to eflect replenishing of the liquid therein during said delay.

2i. In a well pumping system, a motor cylinder, an inlet thereto, a reciprocal motor member in said cylinder arranged to close said inlet when positioned adjacent thereto, a passageway permitting flow to the operating side oi said motor member when said inlet is closed, a balancing tank to be connected to said cylinder, a pump arranged between said tank and cylinder for directing operating liquid irom one to the other in a closed system, a first means to effect normal reversal of ilow between said tank and cylinder when the quantity of operating liquid in the closed system'is above a predetermined amount, a second means to delay the effect of said last named means when said cylinder inlet is closedby said motor member by reason of a reduced quantity of operating liquid..an indeliquid, and connecting means responsive to the closing of said cylinder inlet to open said supply to said closed system to effect replenishing oi the liquid therein during said delay, said first means being arranged to nullify the delay efiect of said second means in response to an increase in the quantity of liquid in said closed system.

22. In a well pumping system, a motor cylinder, a balancing tank, a pump and conduits for passing a body of liquid from said cylinder to said tank and vice versa in a closed system, a

reciprocal motor member in said cylinder, the stroke of which is responsive to the quantity of said body 0! liquid, a first means to effect normal reversal of flow between said tank and cylinder when the quantity of operating liquid is above a predetermined volume, a second means operative to delay the eflect of said last named means, an independent supply of liquid, connecting means operative to connect said closed system with said supply, said second means and said being pressure responsive members subject to pressure at the pump inlet during one stroke of said motor member and being rendered operative by reduction in such pressure, and means to close said pump inlet from the motor cylinder upon predetermined reduction in the quantity of said body of liquid thereby causply of liquid, and connecting means responsive to ing said reduced pressure. 

